The biggest dinosaurs were big eaters, new exhibit at Prairiefire shows

Its body could weigh 20 tons but its brain weighed less than a deck of cards.

The dinosaur that most adults learned to identify as a brontosaurus — it is properly called an apatosaurus — was of a group called sauropods. They were the largest animals ever to walk the Earth. They weren’t the brightest, but they managed to thrive for about 140 million years.

“Even though they had small brains we know that they had fairly advanced behavior,” said Mark Norell, curator of a new exhibit opening Saturday at the Museum at Prairiefire in Overland Park. “They cared for their young, for instance. They were still capable of complex behavior.”

“The World’s Largest Dinosaurs” exhibit was developed by the American Museum of Natural History in New York. It explains how animals so big worked as biological mechanisms.

“Usually when people think of dinosaur shows they think of skeletons or they think of dinosaurs from a specific place,” said Norell, chairman of the Division of Paleontology at the natural history museum and a dinosaur digger himself. “Sauropods are by far the biggest thing ever to walk in the terrestrial realm and there are a lot of interesting scientific questions to ask. How did their circulatory system work? How did their respiratory system work?

“We can transmit a lot of science to people who might not necessarily be interested in science all the time. But, because they like dinosaurs, they’ll come here and hopefully go away with a deeper understanding not only about the biology of these animals but also a basic sense of how the world works.”

The centerpiece of the exhibit is a life-size model (60 feet) of a female adolescent mamenchisaurus. Workers on Thursday were touching up the seams where the various parts of the traveling display had been assembled. Another member of the crew was fine-tuning a video projection onto the side of the beast that will explain the internal workings of the body.

The model is surrounded by various stations that include hands-on activities, including a fossil dig pit. There are some real fossils, too. A 6-foot femur from a camarasaurus stands in a case, but visitors can touch fossilized dinosaur eggshell fragments.

We know from fossil footprints that sauropods lived in herds.

“Not only did they live in herds, they lived in structured herds,” Norell said. “When they’re moving, all the big ones are out at the edges and the small ones are in the middle.”

We don’t know if they had a hierarchy

The main advantage of being large is you have few, if any, predators. That was important during the Jurassic Period.

But if you’re a mamenchisaurus it also means you need to consume 100,000 or so calories a day by fermenting about 1,000 pounds of conifers, ferns and ginkgos in your stomach.

“They didn’t chew, they bulk fed,” Norell said. “Their teeth are mostly pointed and are like big rakes. They would pull off tremendous amounts of food which would be immediately ingested. These guys would just swallow it.”

Dinosaur movies and cartoons like to depict sauropods craning their long necks upward to feed off the tops of trees.

“That’s not true at all,” Norell said.

The huge weight and the need to pump blood to the head made that impossible. And fossil neck vertebrae show the bones would not have fit together vertically. Instead, paleontologists believe, sauropods held their necks more horizontally.

“It’s important if you’re really big to save energy,” Norell said. “You don’t want to move too much. A long neck is beneficial. You can stand in one place and just stick your neck out. You expend very little energy to acquire a large amount of food.”

This story was originally published February 9, 2017 at 6:34 PM with the headline "The biggest dinosaurs were big eaters, new exhibit at Prairiefire shows."